Device for rounding cutout pieces of very thin sheet metal

ABSTRACT

A DEVICE FOR FOLDING THE END PORTION OF A METAL SHEET BY A RELATIVELY LARGE ANGLE, PREFERABLY AN ANGLE IN EXCESS OF 135*. THE DEVICE IS CHARACTERIZED PRIMARILY BY THE ARRANGEMENT OF A SINGLE FOLDING RAIL WHICH HAS A NOSE PORTION AND AN INCLINED SURFACE PORTION AND THE MOVEMENT OF WHICH IS SO CONTROLLED THAT FIRST THE SAID NOSE PORTIONS FOLDS THE RESPECTIVE METAL SHEET END PORTION BY 90* AND SUBSEQUENTLY THE SAID INCLINED SURFACE PORTION   FOLDS THE THUS FOLDED END PORTION BEYOND SAID 90* TO THE DESIRED TOTAL FOLDING ANGLE.

W. SOMMER Jam s, 1971 DEVICE FOR ROUNDING CUTOUT PIECES OF VERY THINSHEET MIE'IAL Filed Sept. 11, 1967 1/ m F w 5 Y u A Z B fl fl MM m. A

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United States Patent U.S. Cl. 72312 3 Claims ABSTRACT OF THE DISCLOSUREA device for folding the end portion of a metal sheet by a relativelylarge angle, preferably an angle in excess of 135. The device ischaracterized primarily by the arrangement of a single folding railwhich has a nose portion and an inclined surface portion and themovement of which is so controlled that first the said nose portionfolds the respective metal sheet end portion by 90 and subsequently thesaid inclined surface portion folds the thus folded end portion beyondsaid 90 to the desired total folding angle.

The present invention concerns a device for rounding, folding or bendingthe edges of pieces cutout of very thin sheet metal, by large angles,preferably by angles exceeding 135 by means of movable folding rails. By

means of devices of the just mentioned type, rectangularly shaped cutoutfine sheet metal pieces which are to be processed to folded can bodiesare rounded for preparing the fold on two oppositely located sides inoppositely pointing directions. Heretofore known devices of this typeoperate with folding rails which are movable in a single directiontransverse or at an angle with regard to the plane of the cutout pieceto be folded. However, with devices of the above-mentioned type it ispossible within a single working operation to obtain a proper rounding,folding or bending only up to an angle of a maximum of 135 whereas forthe rounding, folding or bending of larger angles, for instance thefrequently desired angle. 'of' 150, two working operations are required.In this instance it is necessary by means of a first folding rail tofold about 90 whereupon the thus formed hook is to be folded further bya second folding rail by about 60".

It is an object of the present invention to provide a device of theabove mentioned type which will overcome the above mentioned drawback.

It is another object of this invention to provide a device for roundingthe edges of fine sheet metal pieces by any desired angle in a singleworking operation.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawing, in which:

- FIGS. 1 and 2 respectively illustrate the device according to thepresent invention in two different positions, namely prior to the startof the rounding, folding or bending operation and after the roundingoperation has been completed.

priority, application Germany, Sept. 10, 1966, I

FIG. 3 shows the folding rail in three different positions relative tothe piece to be rounded, the scale of FIG. 3 being considerably largerthan that of FIGS. 1 and 2.

The above outlined objects have been realized according to the presentinvention by the provision of a single folding rail which is so shapedand which is so moved that theportion of the piece to be folded is firstbent by means of a nose by and is subsequently pressed against aninclined surface of the folding rail which inclined surface extendsapproximately in the direction of the desired deviation.

In the device according to the present invention, thus the folding railis not moved in a single direction, i.e., rectilinearly, but is movedalong a curve. According to a further development of the presentinvention, this curve is in the form of an approximately ellipticallycurved portion of a coupling curve which is produced by a fourbarlinkage with oscillating driving crank.

The clamping device for the cutout piece to be folded is advantageouslyso designed that it is opened by the folding rail itself against aspring force as soon as the folding operation is completed.

Referring now to the drawing in detail, the arrangement shown thereincomprises two clamping rails 1 and 2 for clamping the cutout piece ormetal sheet 3 therein. The said rails 1 and 2 are connected to thehousing 4 and cover 5. By means of dish springs 6 carried by the head ofa threaded bolt 7 which can be raised and lowered by means of a nut 7a,the cover 5 and the housing 4 can be pressed against each other with theresult that the two clamping rails 2 and 1 are resiliently pressedagainst the piece 3.

Two eccentric shafts 8 and 9 are arranged parallel to each other in thehousing 4. The first eccentric shaft 8 is adapted to be turned back andforth by about 90 by means of a drive comprising a connecting rod 10, arack 11 and a gear 12. Mounted on the respective eccentricesin FIGS. 1and 2 indicated by their centers 13 and 14 and the centers 13, 14' ofthe shafts 8, 9, respectively-is a link member 15 which isdiagrammatically illustrated in FIGS 1a and 2a of the drawing,corresponding to the FIGS. 1 and 2, respectively. Connected to said linkmember is a folding rail 15a. This folding rail 15a has a surface 16extending transverse to the plane of the piece 3 to be rounded. The saidsurface 16 serves in its starting position (FIG. 1) as abutment for theedge of the piece to be rounded and merges through a nose 17 with aninclined surface 18. By means of an adjacent further surface 19, therail 15a will in the starting position of FIG. 1 lift an abutment screw20 screwed into the cover 5 and will thus also lift the cover 5 with theclamping rail 2 so that it is possible to introduce a new cutout piece.The movement of the rail 15a which is required for folding the piece 3is effected by means of the rocker mechanism which consists of shafts 8and 9, the eccentrics 13 and 14 pertaining thereto and the link member15 mounted on said eccentrics. This folding operation is produced by thefact that in view of the upward movement of the connecting rod 10, theshaft 8 is turned from its starting position shown in FIG. 1 in whichthe center 13 of the respective eccentric is located on the right-handside of and adjacent to the pivot axis of shaft 8 in clockwise directionby 90 until it has reached its position shown in FIG. 2. The nose 17 ofthe folding rail which, as is evident from FIGS. 1 and 2, is locatedapproximately on the extension of the connnecting line between points 13and 14, moves along an elliptical curve section of a so-called couplingcurve which elliptical curve section is shown in FIG. 3 on a largerscale and is designated with the reference numeral 21. With thismovement, as will be evident from FIG. 3, the free end of the cutoutpiece or metal sheet 3 is first bent downwardly and subsequently ispulled over the back of the nose 17 until eventually it has assumed thedirection of the adjacent inclined surface 18. Thereupon, the rail 15amoves back on the same path and after having reached the startingposition shown in FIG. 1 lifts the cover 5 with the clamping rail 2again so that the folded metal sheet 3 in its direction perpendicular tothe drawing plane can be removed and can be replaced by a new one.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular construction shown in the drawing butalso comprises any modifications within the scope of the invention.

I claim:

1. A device for folding the end portion of a metal sheet at an anglegreater than 90, comprising a frame, two clamping rail means mounted onsaid frame and having opposed clamping surfaces for clamping a metalsheet therebetween, said clamping rail means being movable toward eachother into clamping position and away from each other into releasingposition for clamping and releasing a metal sheet between said surfaces,at least one of said clamping rail means having an edge extending fromits clamping surface forming an angle with said clamping surface greaterthan 90 and at least as great as the angle to which the end of the metalsheet is to be folded, a folding rail arranged opposite said clampingrail means and comprising a nose portion projecting toward said clampingrail means and an adjacent inclined portion, and control means includinga link member fixed to said folding rail forming one element of afour-bar linkage, and two eccentrics on which said link member ismounted, said two eccentrics being rotatably mounted on said frame andforming two elements of said four-bar linkage, and means to operate saideccentrics to cause said folding rail to move transversely of saidclamping surfaces and a sheet metal end held therebetween to bend saidsheet metal end transversely, said eccentrics further moving saidfolding rail toward said clamping rail means to engage said sheet metalend with said inclined surface to fold said sheet metal end over saidedge of one of said clamping rail means, thereby forming an anglesubstantially the same as the angle of the edge of said rail means.

2. A device in combination according to claim 1, in which said controlmeans is operable to move said folding rail over an elliptically curvedportion of a coupling curve.

3. A device in combination according to claim 1, which includesadditional means operatively connected to one of said clamping railmeans and operable by said folding rail at the end of each folding cyclefor automatically moving said clamping rail means relative to each otherresiliently into said releasing position.

References Cited UNITED STATES PATENTS 1,055,973 3/1913 Graham ll3ll2,569,181 9/1951 Laxo 72-312 3,058,512 10/1962 Chebuhar et a1. 72305LOWELL A. LARSON, Primary Examiner U.S.Cl. X.R. 723 19

